1. Field of the Invention
This invention relates to a food mixing apparatus for automatically mixing food placed in a mixing container, such as rice and vinegar, or pasta and sauce.
2. Description of the Related Art
A known food mixing apparatus, as disclosed in Japanese Patent Laying-Open Publication H10-99033, for example, includes a rotary container in the form of a bottomed cylinder for receiving food, a rotor ring connected peripherally of the rotary container and having a fore and aft axis inclined relative to the axis of the rotary container, and a main body for supporting the rotor ring to be rotatable about its axis. The main body of the food mixing apparatus has three support rollers for rotatably supporting the rotor ring at right, left and lower peripheries thereof. The lower support roller is connected to a drive motor to be rotatable by the drive motor. The rotation is transmitted by friction to the rotor ring, thereby to rotate the rotor ring and mixing container.
In the above food mixing apparatus, the mixing container, with its axis inclined relative to the axis of the rotor ring, rotates in a precession, successively directing a front opening thereof obliquely upward, obliquely sideways, obliquely downward and obliquely sideways. As a result, the food in the mixing container is mixed efficiently while being moved up and down and fore and aft.
However, the shifting of the center of gravity occurring with the precession wobbles the mixing container from side to side, to wear the right and left support rollers quickly. When the wear creates large gaps between the rotor ring and right and left support rollers, the rotor ring intermittently and repeatedly contacts (i.e. collides with) the support rollers to produce strong vibration and loud noise. In addition, sliding contact occurs with increased frequency therebetween, which contributes to the wear of the support rollers. Another disadvantage is that slippage and a shortage of friction drive could occur since the mixing container is rotated only by the support roller under the rotor ring.
The entire apparatus has a large width and cannot be formed compact, with the support rollers arranged in the right and left outer positions of the rotor ring. Spilt food, dust and the like may deposit below the mixing container, and the lower surface of the mixing container may become stained. The lower support roller is obstructive to a cleaning operation for removing such deposits and stains.
The object of this invention is to provide a food mixing apparatus which advantageously checks wear of support rollers and vibration of a mixing container, and which is formed compact, has improved maintainability, and has a reduced drive transmission loss.
A food mixing apparatus according to this invention comprises a main housing, a mixing container for receiving food, and having a central axis: Y, a rotor ring surrounding the mixing container, the rotor ring being fixed to the mixing container and having a central axis: X extending at an angle to the central axis: Y of the mixing container, and a support roller mechanism attached to the main housing, the support roller mechanism supporting the rotor ring at two points only from below to rotate the rotor ring about the axis: X.
With the above construction in which the rotor ring is supported at two points from below, the mixing container is effectively restrained from wobbling when in rotation, with the aid of its own weight. Even when rollers of the support roller mechanism are worn, the rotor ring is pressed against the rollers by gravity to eliminate the possibility of forming gaps between the rollers and rotor ring, thereby preventing vibration and noise. There is little possibility of the support roller mechanism protruding from the width of the rotor ring, which allows the entire apparatus to be compact. With the support roller mechanism contained in the width of the rotor ring, the maximum width of the apparatus may be made as close to the right and left width of the rotor ring as possible.
In a preferred embodiment of this invention, the support roller mechanism includes a first support roller and a second support roller for rotating the rotor ring, the first support roller and the second support roller being arranged in mirror symmetry about a vertical line. With this construction, a lower portion of the rotor ring fits between the first and second support rollers spaced apart transversely of the apparatus. Thus, the rotor ring is rotatably and stably supported by the support roller mechanism. Two support rollers are sufficient according to this composition. The number of support rollers is less than in the prior art, thereby achieving a cost reduction.
Furthermore, a space is formed between the first and second support rollers. This space facilitates removal of dust and the like collected below the mixing container, and cleaning of a lower portion of the mixing container, thereby improving maintainability. The main housing may include a post portion in form of a rectangular parallelepiped, and a table portion having a skirt surface sloping downward from a middle front surface of the post portion, the support roller mechanism having rollers protruding upward from the skirt surface, and the mixing container being disposed above the skirt surface through the rotor ring. Then, dust and the like lodged on the skirt surface may be removed from between the first and second support rollers by utilizing the slope, thereby facilitating a cleaning operation.
The support roller mechanism may include a first support roller and a second support roller for rotating the rotor ring in a predetermined direction of rotation, the first support roller acting as a drive roller and the second support roller acting as a driven roller, the first support roller being disposed forwardly of the second support roller with respect to the predetermined direction of rotation. Then, the drive roller has a driving vector directed upward. This restrains slippage between the drive roller and rotor ring, and avoids transmission loss and wear.
Of course, both support rollers may act as drive rollers. This construction will increase friction transmission to prevent reliably a transmission loss due to slippage.
In a further preferred embodiment of this invention, the mixing container includes a shaft extending outwardly from a bottom surface thereof and coaxially with the axis: X of the rotor ring, the shaft being rotatably supported by the main housing. With this construction, the mixing container is steadily rotatable through the rotor ring. Further, the shaft may be an aerating tube communicating with an opening formed in the bottom surface of the mixing container, the aerating tube communicating with a blast duct mounted in the main housing. Air flows may be supplied to the mixing container in rotation, thereby cooling, heating or flavoring the food to be mixed. In preparing tasty sushi rice, for example, cool air is essential when mixing boiled rice and vinegar.
Other features and advantages of this invention will be apparent from the following description of the embodiments to be taken with reference to the drawings.